1. Field of the Invention
This invention relates generally to the biological treatment of ordnance or explosives to improve the environmental character thereof and, in particular, to the degradation of TNT (2,4,6-Trinitrotoluene) by using Phanerochaete chrysosporium or white-rot fungus to convert TNT to CO.sub.2.
2. Description of the Prior Art
The compound TNT (2,4,6-trinitrotoluene) is the predominant conventional explosive used by military forces. Unfortunately, past practices for the disposal of TNT generated during the production of TNT and of military ordnance which use TNT have led to soil, sediment, and water contamination. This is of concern because exposure to TNT can cause diseases such as pancytopenia, a disorder of the blood forming tissues characterized by a pronounced decrease in the number of leukocytes, erythrocytes and reticulocytes in the human body. In addition, TNT is known to be toxic to fish such as bluegills at concentrations of 2 to 3 micrograms per milliliter, certain green algae such as Microcystis aeruoinosa and oysters.
In the past TNT has been treated by methods such as the invention disclosed in U.S. Pat. No. 4,038,116 to Andrews et.al. U.S. Pat. No. 4,038,116 discloses a method for treating an aqueous solution of aromatic explosives whereby explosive molecules, such as TNT, are destroyed, and the resulting effluent is safe for disposal. An additive, such as acetone or hydrogen peroxide, is added to an aqueous solution of an aromatic explosive and this mixture is exposed to ultraviolet light. The light exposure of the additive provides a free radical which strips hydrogen molecules from the aromatic explosive to change the aromatic explosive to an unstable intermediate compound. Continued exposure of the unstable intermediate compound to ultraviolet light converts the unstable intermediate compound to carbon dioxide and ammonia. While satisfactory for its intended purpose, that of disposing of aromatic explosives such as TNT, the invention of U.S. Pat. No. 4,038,116 is not very efficient for large scale treatment of contaminated waste disposal sites, can require a considerable expenditure of funds to obtain the required materials and equipment and has obvious limitations, particularly when it is required to treat soil contaminated with TNT.
It is therefore an object of the present invention to provide a relatively inexpensive and efficient method for disposing of waste discharges containing the explosive TNT.
It is further an object of the present invention to provide an ecologically acceptable method of disposing of waste discharges containing TNT by biodegrading the TNT using white rot fungus to convert TNT to carbon dioxide (CO.sub.2).
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the present invention.